The Development of Optical Biosensors for the detection of proteins in solution

Toole, Nicola Jayne (2024). The Development of Optical Biosensors for the detection of proteins in solution. University of Birmingham. Ph.D.

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Abstract

Biosensors for use in point of care (POC) settings are highly sought after; yet, fabrication is often difficult due to costly materials. Hydrogels can be prepared using cheap and commercially available materials. Leaky waveguide (LW) biosensors have been developed previously using hydrogels, leading to the formation of label-free, real-time optical biosensors from readily available materials. If the instrumentation required for these devices was smaller and more user friendly, then LWs would be ideal for POC diagnostics.
In order to improve the portability of LWs for POC testing, the useability of a three dimensional (3D) printed instrument for the testing of hydrogel-based LW devices was studied. This included comparing the refractive index sensitivity (RIS) and porosity of LWs tested on a traditional benchtop laboratory-based instrument to those tested using a 3D printed instrument. The 3D printed instrument was also then tested for the ability to detect biologically relevant analytes, in the form of immunoglobulin G (IgG).
The structure of the 3D printed instrument eliminated the ability to use a two-channel flow cell to incorporate an internal reference, which is a requirement for the user-friendly data analysis. The internal reference allows for the subtraction of signals caused by nonspecific binding from the detection signal, giving an accurate representation of binding due to the desired immobilisation strategy. In order to address this, LWs comprised of photocaged hydrogels were investigated. Following this, photolabile protecting groups (PPGs) were designed and used to photocage monomers.
LWs were then created using these photocaged monomers, prior to selective photodeprotection of the PPGs to release protein reactive functional groups. This incorporated a reference internally within the LW device through the production of protein reactive and protein inert regions. These internally referenced LW biosensors were then tested for their ability to act as biosensors.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):